am

I wanted to order kits to rebuild my calipers and new pads too but the guy told me there were two kinds of calipers S or M , how do i do to identify what kind i have ?

ebsalem

If they're magnetic 'M'

If not 'S'

am

Thank's , simple but could you explain me the difference ?

madmmac

M calipers are the stock, steel calipers for 911’s through 75. Caliper mounting bolt spacing on strut is about 3 inches.

S calipers are made out of aluminum and are bigger calipers used on the 911S and ‘S’ option cars through 77. Bolt spacing on strut is about 3.5 inches.

theiceman

I guess he means if a magnet will stick to them they are the steel ones, if it doesn't they are alluminum..

Peter Zimmermann

Just a thought... Because the fastener system between front ball joint and strut on your year car (1970) is unreliable, this situation is often corrected on modified cars by using later model (SC, etc., struts). If this is the case your front calipers will be "A" type. Check the bottom of your front struts, do they have a pinch bolt design just above the ball joint, or do they have a "pin" with a lock nut? If your car has red struts, or re-worked Sportomatic struts that now use shock inserts, they probably started life with aluminum "S" calipers. Because of repair difficulties, many of those calipers have been replaced with "A" calipers. Aluminum "S" calipers are extremely valuable, but the inner piston housings often have deep wear grooves, which require special machined inserts to repair. If your car has green (Bilstein) struts they will almost always be fitted with "A" calipers.
Pete

am

Thank you guys for these precious infos and sorry for the delay to answer , i did'nt touch the car during the last weeks
If i rely on your informations my calipers are the M type but i'm kind of confused with the A type possibility so i sent pix.